Fire alarm dispatching mechanism



April 13, 1937. J. F. EBERT er AL FIRE ALARM DISPATCHIKG MECHAN IS M Filed Aug. 25 1934 Patented Apr. 13, 1937 v UNITED STATES PAT NT OFFICE FIRE DISPATCHING MECHANISM Application August 23, 1934,'Serial No. 141,140.

4 Claims. (01. 135-37) The present invention relates to fire alarms,

I and more particularly to the dispatching mechanism for a fire alarm box, by theoperation of which a given code signal is sent to fire headquarters, or transmitted to different stations in the system.

In apparatus of this type as heretofore constructed, the dispatching mechanism of a call box is usually set in operation by a hand lever, movement of the lever causing a spring to be wound, after which, upon release of the lever, the spring acting through suitable gearing actuates the dispatching mechanism to send the code by means of a rotating code wheel. In a fire alarm system employing a large number of call boxes, each having a different code number, it is desirable to be able to regulate the rate of rotation of the code wheels of the several call boxes in accordance with the number of impulses in the different code calls, so that the different code signals will betransmitted with substantially uniform intervals between code impulses.

According to the present invention, there is provided an improved dispatchingmechanism for a fire alarm box, in which the rate of rotation of the code wheel shaft may be readily adjusted to give the desired intervals between code impulses to be transmitted by a given box. In addition, the invention provides means whereby the element determining the code sequence may be readily removed and another element substituted therefor in order to change the code number of a particular box, without in any way disturbing any part of the dispatching mechanism. The above and other advantageous features of the invention will hereinafter more fully appear from the following description taken in connection with the accompanying drawing, in which:-

Fig. 1 is a'view in elevation of a dispatching mechanism embodying the invention, as seen from the code Wheel side.

Fig. 2 is a view in side elevation of the parts shown in Fig. 1, as viewed from the left.

Fig. 3 is a view in-elevation as seen from the left of Fig. 2, with one frame plate removed.

Fig. 4 is a fragmentary, view illustrating the manner of controlling the speed of the dispatching mechanism.

Fig. ,5 is a fragmentaryview illustrating the mounting of the code wheel.

. Fig. 6 shows the code wheel of Fig. 5 removed from its driving shaft.

Like reference characters refer to like parts Iin the different figures. t, Referring first to Figs. 1, 2 and 3, the dispatching mechanism, shown as having been removed 7 from the fire alarm box in which it is normally mounted, is adapted to be actuated by a hand lever I which is accessible from the front of the box. turning of the lever in the direction of the arrow in Fig. 1 causes a, toothed sector 3 on the shaft 2 to turn a pinion 4 mounted on a shaft 5. The shaft 5 also is connected to a spring 6, shown in dotted lines, within a casing to carried by the frame plate ,I, and this spring is wound by turning of the lever I. Consequently, upon release of the lever I at the end of its downward movement, the tension of the spring 6 on the shaft 5 actuates the dispatching mechanism to send a predetermined signal.

The shaft 5 also carries a gear 8 in mesh with a pinion 9 on a shaft II! on which is also mounted a code wheel II, the detailed construction of which will be hereinafter described. The code wheel shaft I0 is also connected by gearing I2 to a shaft I3 on which is mounted an escapement wheel M, the ratio of gearing I2 being such that the escapement wheel shaft I3 rotates at a considerably higher speed than the cam wheel shaft III. The teeth Ida of the escapement wheel I4 are adapted to be engaged by an escapement pawl I5 mounted on a shaft I6, and the operation of the pawl I5 is such that rotation of the wheel I4 is converted into oscillatory movement of the shaft l6. 1 I

As best shown in Figs. 1 and 4, the escapement pawl shaft I6 extends through the frame plate 'I and is provided at its upper end with a slot ll.

1 An arm I8 is received in this slot II, with one end of the arm frictionally clamped by means of a set screw I9 extending through the walls of the slot II. The other end of the arm I8 terminates in a ball portion 28 that is received in alined grooves 2I provided in opposed faces of a pair of disks 22. The disks 22 are secured together, and are freely mounted on a shaft 23, so that when the escapement pawl shaft I6 is oscillated by the wheel I4, an oscillatory movement is also imparted to the disks 22 by the arm IS.

As is evident from Fig. l, the amplitude of the oscillatory movement of the disks 22 for a given amplitude of movement of the shaft I6 is determined by the setting of the arm Iii in the slot .II. That is to say, the farther the ball portion 20 the oscillatory movement of the disks 22 and vice versa. Since the disks 22 possess considerable inertia, it therefore follows that the greater the The lever I ismounted on a shaft 2, and

is displaced from the axis of the'escapement pawl shaft I6, the greater will be the amplitude of amplitude of movement of the disks 22, the greater will be the damping effect exerted by the disks on rotation of the code wheel shaft l0. Conversely, decreasing the amplitude of oscillation of the disks 22 will tend to speed up the shaft l0. Therefore, the arm I8 cooperating with the disk 22 provides means whereby the speed of the code wheel shaft l0 may be regulated. Stated another way, it has been found that with the arm l8 set to position the ball portion 20 at the ends of the grooves 2| farthest removed from the axis of the shaft IS, the shaft ID will rotate for approximately two minutes, for one winding of the spring 6 by the lever On the other hand, with the ball portion 20 located at the ends of the grooves 2| nearest the shaft IS, the shaft ID will rotate only thirty seconds, for one winding of spring 6, with intermediate periods of rotation obtainable for different settings of the ball portion 20 in the grooves 2|.

As best shown in Fig. l, the code wheel provides around its periphery a number of code determining projections lla, and rotation of the wheel I causes these projections Ila to operate a pivotally mounted arm 24. The arm 24 provides a projection 25, which is disposed between a pair of contact members 26 and 21. Normally, contact tips 26a and 21a on these contact members 26 and 21 are in engagement as shown, but when a code projection I la engages the arm 24, turning of the latter in a clockwise direction about its pivot 24a causes the arm projection 25 to disengage the contact tip 21a from the contact tip 26a. As the projections Ila on the code wheel successively engage the arm 24, an oscillatory movement is imparted to the arm 24 which results in successive engagement and disengagement of the contact members 26 and 21. This operation of the contacts causes signal impulses to be transmitted through the system, in which the fire alarm box is connected, which system forms no part of the present invention. Since the number of projections a on the code wheel II will vary for different fire alarm boxes, it is possible by regulating the speed of the code wheel shaft ID, in the manner described above, to cause the signal impulses to be transmitted with the desired intervals therebetween. Obviously, the arm I8 provides means for readily obtaining such speed regulation, without in any way disturbing other portions of the dispatching mechanism.

As previously pointed out, the present invention also contemplates an improved mounting of the code wheel whereby the latter may readily be removed from the shaft l0, and this mounting is best shown in Figs. 5 and 6. To this end, the wheel carries a bracket 28 having an opening 29 extending therethrough for freely receiving the projecting end of the shaft Ill. The bracket 28 also provides a slot 30 for receiving a pin 3| extending transversely through the shaft I0. Therefore, when the shaft I0 is passed through the opening 29 in the bracket 28 with the pin 3| received in the slot 30, the code wheel H is adapted to rotate with the shaft 0. After a code wheel I I has been so positioned on the shaft, it is secured against removal therefrom by turning set to loosen the screws 32 and withdraw the wheel from the shaft l0. Then when a wheel having a different code determination is placed on the shaft, the pin 3| engaging with the slot 30 of the new wheel insures that the new wheel will occupy exactly the same angular position on the shaft 0 as did the wheel just removed. This insures that when code wheels are changed on the dispatching mechanism, there is no possibility of the code being mis-sent by the new wheel, owing to it being positioned on the shaft I0 in the wrong angular relation with respect to the contact operating arm 24.

From the foregoing, it is apparent that by the present invention there is provided an improved fire alarm dispatching mechanism characterized by the fact that the speed with which signal impulses are transmitted thereby may be conveniently regulated without in any way disturbing the arrangement, or functioning, of the mechanism. Furthermore, the code determining element of the mechanism can be quickly removed and a different element substituted therefor without any possibility of the substitution causing any disturbance in the timing of the mechanism, when operated.

We claim,

1. In a motor for driving a fire alarm dispatching mechanism, the combination with a rotatably mounted shaft for the purpose of carrying a code wheel and a train of gearing for driving said shaft, said gearing being operated by a spring which is wound upon actuation of the mechanism, of a shaft carrying an escapement pawl for converting rotation of one member of said gear train into oscillatory movement of said escapement shaft, a rotatably mounted damping disk and an adjustable link extending between the surface of said disk and the axis of said escapement shaft for regulating the speed of rotation of said code wheel shaft.

2. In a motor for driving a fire alarm dispatching mechanism, the combination with a rotatably mounted shaft for the purpose of carrying a code wheel and a train of gearing for driving said shaft, said gearing being operated by a spring which is wound upon actuation of the mechanism, of a shaft carrying an'escapement pawl for converting rotation of one member of the gear train intooscillatory movement of the shaft, a rotatably mounted damping disk and an arm adjustably carried by said escapement shaft and having its free end loosely connected to said disk for converting oscillatory movement of said shaft into oscillatory movement of said disk, the

effective length of said arm being adapted to determine the amplitude of the oscillatory movement of said disk.

3. In a speed controlling mechanism for spring motors, the combination with a spring driven train of gearing and a shaft carrying an escapement pawl for converting rotation of one member of said gear train into oscillatory movement of the escapement shaft, of a freely mounted damping disk having a slot therein, and an arm extending from said escapement shaft having its free end received in said slot, said arm being radially adjustable on said shaft, with the position of the free end of the arm in said slot determining the amount of damping eifect exerted by said disk on the oscillatory movement of said escapement shaft.

4. In a speed controlling mechanism for spring motors, the combination with a spring driven means for clamping said arm on said shaft with its rounded end at different distances from the axis of said shaft to vary the amplitude of oscillation of said damping disk.

JOSEPH F. EBERT. TELLEF A. 'IERJESEN. 

